In a liquid container according to a related art, when a side surface of the liquid container is pressurized, a content within an inner space of the container is discharged through a discharge hole of a lid. Also, when the side surface of the liquid container is not pressurized, the side surface is returned to its original state. Here, there is a common technology that a portion of the contents remaining around the discharge hole of the lid is suctioned into the inner space of the container while the constricted volume of the inner space of the container is restored.
However, there is a technical defect in that the side surface has to have a predetermined thickness to ensure pressurization and restoring performances thereof.
Also, when the side surface has a too thick thickness, the elderly persons or child may be difficult to use the container. On the other hand, when the side surface has a too thin thickness, the side surface may be reduced in restoring performance to allow the contents to be stained around the discharge hole of the lid, and thus it is unsanitary.
To solve the above-described defect, a technology that a mark having a slightly recessed shape is disposed on a certain portion of the side surface of a container body, and the certain portion is constantly pressurized is proposed in a related document (see PCT/US2010/048449). However, it may not be realistic because it is uncomfortable that the user looks at and pressurizes the certain portion. Here, the certain portion, is just the mark such as a picture or a symbol.